Crude oils, crude distillates (e.g. gas oil, petroleum fuel, diesel oil, heating oil, kerosene, etc. . . . ), residual fuels and/or residual oils often contain waxy constituents which can precipitate when the crude oil, crude distillate, residual fuel and/or residual oil are subjected to lower temperatures. Depending upon the particular composition, crude oil, crude oil distillates, residual fuels and/or residual oils can lose their fluidity as the waxy constituents precipitate from the bulk solution. The precipitation of the waxy constitutes can cause problems during the recovery, transport, storage and/or use of the crude oils, crude oil distillates, and/or residual oils. In crude oil recovery and transport, the wax precipitates can deposit on pipeline walls causing difficulty in pumping and in some cases complete blockage of the pipeline which can be a particular concern for the transport of crude oil in areas having low temperatures (e.g. sub arctic areas). In storage and further processing of crude oils, the precipitates can necessitate heated storage for the crude oils, crude oil distillates, residual fuels, and residual oils to limit settling and agglomeration of the wax precipitates. In use, the waxy constituents can result in formation of precipitates in storage tanks, cause plugged transport or fuel lines, and/or block filters in engines and furnaces, preventing reliable metering of the fuels and in some cases causing complete interruption of the supply of the fuel or heating medium.
The problems associated with the loss of fluidity of hydrocarbon oils and wax precipitate formation in crude oils, crude oil distillates, residual fuels, and/or residual oils at low temperatures are of considerable concern. Parameters such as pour point, and cloud point are often used to measure the flowability and wax precipitate formation properties of crude oils, crude oil distillates, residual fuels, and/or residual oils. Pour point (ASTM D97-47) is defined as the lowest temperature at which a material will flow when chilled without disturbance under specified conditions while the cloud point (ASTM D 2500) is the temperature at which a precipitates first appear as a haze in a material upon cooling. A material's pour point indicates the temperature at which (if not before) the formation of solid or semi-solid precipitate particles can begin to affect the flowability and/or pumpability of these materials under low temperature conditions making the transport and pumping of the material difficult if not near impossible. A material's cloud point (ASTM D 2500) indicates the temperature at which the waxy constituents having the lowest solubility (typically those having the highest molecular weight) begin to precipitate and can begin create problems in filtering the material.
In order to avoid difficulties with the precipitation of waxy constituents during production, storage, transport, processing, and use, additives are often added to crude oil, crude oil distillates, residual fuel, and/or residual oils to decrease the wax precipitate particle size, change wax precipitate particle structure, reduce settling and/or agglomeration of the wax precipitate particles, and/or maintain or improve their low temperature flow properties. These additives can modify the size, number, and/or growth of the precipitated wax particles in the crude oil, crude oil distillate, residual fuel, and/or residual oil in a way that imparts improved low temperature handling, transport, storage, pumpability, and/or use. In some instances, the additive or combination of additives reduce the pour point of the crude oil, crude oil distillate, residual fuel and/or residual oil. The additive or combinations of additives that reduce pour point are accordingly called pour point depressants.
Generally, pour point depressants do not make the wax constituents more soluble in oil. Rather pour point depressants function by reducing wax particle size, changing wax particle shape, and/or disrupting or preventing the formation of a waxy precipitate network by interacting physically with the precipitating wax. This interaction results in the size, shape, and/or adhesion properties changes in the wax precipitates. Thus, the addition of pour point depressant can ease the pumping, filtering, processing or use of a material at a particular set of conditions or alternatively enable the pumping, filtering, processing or use of a material at conditions under which the material alone cannot.
Many different types of compounds have been used as different pour point depressants including alkylated aromatic compounds, phenol/aldehyde condensation products, olefin oligomers, copolymers of ethylene and alpha olefins, ethylene/propylene polymers that have been oxidized and hydrogenated, ethylene/vinyl acetate based polymers, acrylate based polymers, maleic anhydride/alpha olefin based copolymer, and maleic anhydride/alpha olefin Diels-Alder adduct based compounds, among others. However, many of these materials are polymers and/or high molecular weight materials. Herein is described a simple non-polymeric material which can function as a pour point depressant.